The present disclosure relates to vehicle engines, and particularly to apparatus for venting fumes present in an engine crankcase. More particularly, the present disclosure relates to a Positive Crankcase Ventilation (PCV) valve having a variable-flow orifice.
A PCV valve helps control pollution from vehicles by returning crankcase fumes to the engine's intake manifold to be mixed with incoming filtered combustion air and inducted into the cylinders of the engine. A mixture of crankcase fumes, air, and fuel then is combusted in the engine cylinders during a combustion cycle to power the vehicle engine. Thus, the crankcase fumes are burned and not just discharged into the atmosphere.
During a normal compression stroke of an engine piston in an engine cylinder providing a combustion chamber, a small amount of gases in the combustion chamber escapes past the piston and enters the crankcase. Such “blowby” gases include unburned fuel that can dilute and contaminate engine oil, cause corrosion to engine parts, and contribute to sludge build up in the engine. PCV valves cooperate to remove these blowby gases from the crankcase and combine them with the engine's normal incoming air/fuel mixture before such a mixture is burned in the engine.